Filename: //usr/include/c++/10/experimental/memory_resource

// <experimental/memory_resource> -*- C++ -*- // Copyright (C) 2015-2020 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file experimental/memory_resource * This is a TS C++ Library header. * @ingroup libfund-ts */ #ifndef _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE #define _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 1 #pragma GCC system_header #if __cplusplus >= 201402L #include <memory> // align, uses_allocator, __uses_alloc #include <experimental/utility> // pair, experimental::erased_type #include <atomic> // atomic #include <new> // placement new #include <cstddef> // max_align_t #include <ext/new_allocator.h> #include <debug/assertions.h> /// @cond namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION template<typename _Tp> class malloc_allocator; _GLIBCXX_END_NAMESPACE_VERSION } // namespace __gnu_cxx /// @endcond namespace std { _GLIBCXX_BEGIN_NAMESPACE_VERSION namespace experimental { inline namespace fundamentals_v2 { namespace pmr { #define __cpp_lib_experimental_memory_resources 201402L // Standard memory resources // 8.5 Class memory_resource class memory_resource; // 8.6 Class template polymorphic_allocator template<typename _Tp> class polymorphic_allocator; template<typename _Alloc, typename _Resource = memory_resource> class __resource_adaptor_imp; // 8.7 Alias template resource_adaptor template<typename _Alloc> using resource_adaptor = __resource_adaptor_imp< typename allocator_traits<_Alloc>::template rebind_alloc<char>>; // 8.8 Global memory resources memory_resource* new_delete_resource() noexcept; memory_resource* null_memory_resource() noexcept; memory_resource* get_default_resource() noexcept; memory_resource* set_default_resource(memory_resource* __r) noexcept; // TODO 8.9 Pool resource classes class memory_resource { static constexpr size_t _S_max_align = alignof(max_align_t); public: memory_resource() = default; memory_resource(const memory_resource&) = default; virtual ~memory_resource() = default; memory_resource& operator=(const memory_resource&) = default; _GLIBCXX_NODISCARD void* allocate(size_t __bytes, size_t __alignment = _S_max_align) { return do_allocate(__bytes, __alignment); } void deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align) { return do_deallocate(__p, __bytes, __alignment); } bool is_equal(const memory_resource& __other) const noexcept { return do_is_equal(__other); } protected: virtual void* do_allocate(size_t __bytes, size_t __alignment) = 0; virtual void do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0; virtual bool do_is_equal(const memory_resource& __other) const noexcept = 0; }; inline bool operator==(const memory_resource& __a, const memory_resource& __b) noexcept { return &__a == &__b || __a.is_equal(__b); } inline bool operator!=(const memory_resource& __a, const memory_resource& __b) noexcept { return !(__a == __b); } template<typename _Tp> class polymorphic_allocator { public: using value_type = _Tp; polymorphic_allocator() noexcept : _M_resource(get_default_resource()) { } polymorphic_allocator(memory_resource* __r) : _M_resource(__r) { _GLIBCXX_DEBUG_ASSERT(__r); } polymorphic_allocator(const polymorphic_allocator& __other) = default; template <typename _Up> polymorphic_allocator(const polymorphic_allocator<_Up>& __other) noexcept : _M_resource(__other.resource()) { } polymorphic_allocator& operator=(const polymorphic_allocator& __rhs) = default; _GLIBCXX_NODISCARD _Tp* allocate(size_t __n) { return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp), alignof(_Tp))); } void deallocate(_Tp* __p, size_t __n) { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); } template <typename _Tp1, typename... _Args> //used here void construct(_Tp1* __p, _Args&&... __args) { std::__uses_allocator_construct(this->resource(), __p, std::forward<_Args>(__args)...); } // Specializations for pair using piecewise construction template <typename _Tp1, typename _Tp2, typename... _Args1, typename... _Args2> void construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t, tuple<_Args1...> __x, tuple<_Args2...> __y) { memory_resource* const __resource = this->resource(); auto __x_use_tag = std::__use_alloc<_Tp1, memory_resource*, _Args1...>(__resource); auto __y_use_tag = std::__use_alloc<_Tp2, memory_resource*, _Args2...>(__resource); ::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct, _M_construct_p(__x_use_tag, __x), _M_construct_p(__y_use_tag, __y)); } template <typename _Tp1, typename _Tp2> void construct(pair<_Tp1,_Tp2>* __p) { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); } template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> void construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y) { this->construct(__p, piecewise_construct, forward_as_tuple(std::forward<_Up>(__x)), forward_as_tuple(std::forward<_Vp>(__y))); } template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> void construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr) { this->construct(__p, piecewise_construct, forward_as_tuple(__pr.first), forward_as_tuple(__pr.second)); } template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> void construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr) { this->construct(__p, piecewise_construct, forward_as_tuple(std::forward<_Up>(__pr.first)), forward_as_tuple(std::forward<_Vp>(__pr.second))); } template <typename _Up> void destroy(_Up* __p) { __p->~_Up(); } // Return a default-constructed allocator (no allocator propagation) polymorphic_allocator select_on_container_copy_construction() const { return polymorphic_allocator(); } memory_resource* resource() const { return _M_resource; } private: using __uses_alloc1_ = __uses_alloc1<memory_resource*>; using __uses_alloc2_ = __uses_alloc2<memory_resource*>; template<typename _Tuple> _Tuple&& _M_construct_p(__uses_alloc0, _Tuple& __t) { return std::move(__t); } template<typename... _Args> decltype(auto) _M_construct_p(__uses_alloc1_ __ua, tuple<_Args...>& __t) { return tuple_cat(make_tuple(allocator_arg, *(__ua._M_a)), std::move(__t)); } template<typename... _Args> decltype(auto) _M_construct_p(__uses_alloc2_ __ua, tuple<_Args...>& __t) { return tuple_cat(std::move(__t), make_tuple(*(__ua._M_a))); } memory_resource* _M_resource; }; template <class _Tp1, class _Tp2> bool operator==(const polymorphic_allocator<_Tp1>& __a, const polymorphic_allocator<_Tp2>& __b) noexcept { return *__a.resource() == *__b.resource(); } template <class _Tp1, class _Tp2> bool operator!=(const polymorphic_allocator<_Tp1>& __a, const polymorphic_allocator<_Tp2>& __b) noexcept { return !(__a == __b); } /// @cond undocumented class __resource_adaptor_common { template<typename, typename> friend class __resource_adaptor_imp; struct _AlignMgr { _AlignMgr(size_t __nbytes, size_t __align) : _M_nbytes(__nbytes), _M_align(__align) { } // Total size that needs to be allocated. size_t _M_alloc_size() const { return _M_buf_size() + _M_token_size(); } void* _M_adjust(void* __ptr) const { const auto __orig_ptr = static_cast<char*>(__ptr); size_t __space = _M_buf_size(); // Align the pointer within the buffer: std::align(_M_align, _M_nbytes, __ptr, __space); const auto __aligned_ptr = static_cast<char*>(__ptr); const auto __token_size = _M_token_size(); // Store token immediately after the aligned block: char* const __end = __aligned_ptr + _M_nbytes; if (__token_size == 1) _S_write<unsigned char>(__end, __aligned_ptr - __orig_ptr); else if (__token_size == sizeof(short)) _S_write<unsigned short>(__end, __aligned_ptr - __orig_ptr); else if (__token_size == sizeof(int) && sizeof(int) < sizeof(char*)) _S_write<unsigned int>(__end, __aligned_ptr - __orig_ptr); else // (__token_size == sizeof(char*)) // Just store the original pointer: _S_write<char*>(__end, __orig_ptr); return __aligned_ptr; } char* _M_unadjust(char* __ptr) const { const char* const __end = __ptr + _M_nbytes; char* __orig_ptr; const auto __token_size = _M_token_size(); // Read the token and restore the original pointer: if (__token_size == 1) __orig_ptr = __ptr - _S_read<unsigned char>(__end); else if (__token_size == sizeof(short)) __orig_ptr = __ptr - _S_read<unsigned short>(__end); else if (__token_size == sizeof(int) && sizeof(int) < sizeof(char*)) __orig_ptr = __ptr - _S_read<unsigned int>(__end); else // (__token_size == sizeof(char*)) __orig_ptr = _S_read<char*>(__end); // The adjustment is always less than the requested alignment, // so if that isn't true now then either the wrong size was passed // to deallocate or the token was overwritten by a buffer overflow: __glibcxx_assert(static_cast<size_t>(__ptr - __orig_ptr) < _M_align); return __orig_ptr; } private: size_t _M_nbytes; size_t _M_align; // Number of bytes needed to fit block of given size and alignment. size_t _M_buf_size() const { return _M_nbytes + _M_align - 1; } // Number of additional bytes needed to write the token. int _M_token_size() const { if (_M_align <= (1ul << __CHAR_BIT__)) return 1; if (_M_align <= (1ul << (sizeof(short) * __CHAR_BIT__))) return sizeof(short); if (_M_align <= (1ull << (sizeof(int) * __CHAR_BIT__))) return sizeof(int); return sizeof(char*); } template<typename _Tp> static void _S_write(void* __to, _Tp __val) { __builtin_memcpy(__to, &__val, sizeof(_Tp)); } template<typename _Tp> static _Tp _S_read(const void* __from) { _Tp __val; __builtin_memcpy(&__val, __from, sizeof(_Tp)); return __val; } }; }; /// @endcond // 8.7.1 __resource_adaptor_imp template<typename _Alloc, typename _Resource> class __resource_adaptor_imp : public _Resource, private __resource_adaptor_common { using memory_resource = _Resource; static_assert(is_same<char, typename allocator_traits<_Alloc>::value_type>::value, "Allocator's value_type is char"); static_assert(is_same<char*, typename allocator_traits<_Alloc>::pointer>::value, "Allocator's pointer type is value_type*"); static_assert(is_same<const char*, typename allocator_traits<_Alloc>::const_pointer>::value, "Allocator's const_pointer type is value_type const*"); static_assert(is_same<void*, typename allocator_traits<_Alloc>::void_pointer>::value, "Allocator's void_pointer type is void*"); static_assert(is_same<const void*, typename allocator_traits<_Alloc>::const_void_pointer>::value, "Allocator's const_void_pointer type is void const*"); public: using allocator_type = _Alloc; __resource_adaptor_imp() = default; __resource_adaptor_imp(const __resource_adaptor_imp&) = default; __resource_adaptor_imp(__resource_adaptor_imp&&) = default; explicit __resource_adaptor_imp(const _Alloc& __a2) : _M_alloc(__a2) { } explicit __resource_adaptor_imp(_Alloc&& __a2) : _M_alloc(std::move(__a2)) { } __resource_adaptor_imp& operator=(const __resource_adaptor_imp&) = default; allocator_type get_allocator() const noexcept { return _M_alloc; } protected: virtual void* do_allocate(size_t __bytes, size_t __alignment) override { // Cannot use max_align_t on 32-bit Solaris x86, see PR libstdc++/77691 #if ! ((defined __sun__ || defined __VXWORKS__) && defined __i386__) if (__alignment == alignof(max_align_t)) return _M_allocate<alignof(max_align_t)>(__bytes); #endif switch (__alignment) { case 1: return _M_alloc.allocate(__bytes); case 2: return _M_allocate<2>(__bytes); case 4: return _M_allocate<4>(__bytes); case 8: return _M_allocate<8>(__bytes); } const _AlignMgr __mgr(__bytes, __alignment); // Assume _M_alloc returns 1-byte aligned memory, so allocate enough // space to fit a block of the right size and alignment, plus some // extra bytes to store a token for retrieving the original pointer. return __mgr._M_adjust(_M_alloc.allocate(__mgr._M_alloc_size())); } virtual void do_deallocate(void* __ptr, size_t __bytes, size_t __alignment) noexcept override { #if ! ((defined __sun__ || defined __VXWORKS__) && defined __i386__) if (__alignment == alignof(max_align_t)) return (void) _M_deallocate<alignof(max_align_t)>(__ptr, __bytes); #endif switch (__alignment) { case 1: return (void) _M_alloc.deallocate((char*)__ptr, __bytes); case 2: return (void) _M_deallocate<2>(__ptr, __bytes); case 4: return (void) _M_deallocate<4>(__ptr, __bytes); case 8: return (void) _M_deallocate<8>(__ptr, __bytes); } const _AlignMgr __mgr(__bytes, __alignment); // Use the stored token to retrieve the original pointer. _M_alloc.deallocate(__mgr._M_unadjust((char*)__ptr), __mgr._M_alloc_size()); } virtual bool do_is_equal(const memory_resource& __other) const noexcept override { if (auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other)) return _M_alloc == __p->_M_alloc; return false; } private: template<size_t _Num> struct _Aligned_type { alignas(_Num) char __c[_Num]; }; // Rebind the allocator to the specified type and use it to allocate. template<size_t _Num, typename _Tp = _Aligned_type<_Num>> void* _M_allocate(size_t __bytes) { typename allocator_traits<_Alloc>::template rebind_alloc<_Tp> __a2(_M_alloc); const size_t __n = (__bytes + _Num - 1) / _Num; return __a2.allocate(__n); } // Rebind the allocator to the specified type and use it to deallocate. template<size_t _Num, typename _Tp = _Aligned_type<_Num>> void _M_deallocate(void* __ptr, size_t __bytes) noexcept { typename allocator_traits<_Alloc>::template rebind_alloc<_Tp> __a2(_M_alloc); const size_t __n = (__bytes + _Num - 1) / _Num; __a2.deallocate((_Tp*)__ptr, __n); } _Alloc _M_alloc{}; }; // Global memory resources inline memory_resource* new_delete_resource() noexcept { using type = resource_adaptor<__gnu_cxx::new_allocator<char>>; alignas(type) static unsigned char __buf[sizeof(type)]; static type* __r = new(__buf) type; return __r; } inline memory_resource* null_memory_resource() noexcept { class type final : public memory_resource { void* do_allocate(size_t, size_t) override { std::__throw_bad_alloc(); } void do_deallocate(void*, size_t, size_t) noexcept override { } bool do_is_equal(const memory_resource& __other) const noexcept override { return this == &__other; } }; alignas(type) static unsigned char __buf[sizeof(type)]; static type* __r = new(__buf) type; return __r; } // The default memory resource /// @cond undocumented inline std::atomic<memory_resource*>& __get_default_resource() { using type = atomic<memory_resource*>; alignas(type) static unsigned char __buf[sizeof(type)]; static type* __r = new(__buf) type(new_delete_resource()); return *__r; } /// @endcond /// Get the current default resource. inline memory_resource* get_default_resource() noexcept { return __get_default_resource().load(); } /// Change the default resource and return the previous one. inline memory_resource* set_default_resource(memory_resource* __r) noexcept { if (__r == nullptr) __r = new_delete_resource(); return __get_default_resource().exchange(__r); } } // namespace pmr } // namespace fundamentals_v2 } // namespace experimental _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif // C++14 #endif // _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE

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